ulnar artery

The larger of the two terminal branches of the brachial trunk.
It originates in the cubital fossa, at the level of the
neck of the radius. In the upper third
of the forearm it passes obliquely downward and medially, and then it proceeds
straight down to the wrist. It pierces the
deep fascia immediately above the flexor
retinaculum, and passes on to the front of it, where it gives off
a branch deep and then becomes the superficial palmar arch.

Relations of the ulnar artery

Throughout its entire course the ulnar artery is accompanied by two venae
comitantes. In the upper, oblique portion of its course, the vessel
is deeply placed, and is crossed by both heads of the pronator terres,
the flexor carpi radialis, the palmaris longus,
the flexor digitorum sublimis, and the median
nerve. Its lower, vertical part is overlapped medially by the flexor
carpi ulnaris, but a short distance above the wrist it comes nearer the
surface, and lies behind the deep fascia in the interval between the tendon
of the flexor carpi ulnaris and the tendons of the flexor sublimis. It has
important relations to the median and ulnar
nerves.

In the cubital fossa, the ulnar artery rests on the brachialis;
from there to the wrist it lies on the flexor digitorum profundus; at the
wrist, it lies on the flexor retinaculum.

Branches of
the ulnar artery in the forearm

In addition to the muscular branches, there are several
that are named.

The ulnar recurrent arteries, anterior and posterior, arise
near the elbow, and anastomose with branches
of the brachial artery on the front and back of the medial
epicondyle.

The common interosseous artery is a short, wide trunk which
originates below the recurrent branches, about one inch from the beginning
of the ulnar artery. It passes backward to the upper margin of the interosseous
membrane where it divides.

The posterior interosseous artery passes backward above
the interosseous membrane to the back of the forearm.

The anterior interosseous artery descends over the front
of the interosseous membrane, between the flexor pollicis longus
and the flexor digitorum profundis. At the upper border
of the pronator quadratus, it pierces the interosseous
membrane and passes to the back of the forearm. In addition to muscular
twigs, it supplies nutrient arteries to the radius and ulna,
and gives off the median artery – long and slender – which accompanies
the median nerve.

The carpal branches of the ulnar artery are small arteries
that arise near the wrist. They anastomose with corresponding branches of
the radial artery in the formation of the anterior and posterior
carpal arches.